The invention relates generally to handheld trimmers and, more specifically, to handheld trimmers incorporating glider supports in various configurations.
Existing handheld trimmers typically utilize gas powered, AC or DC motors and a monofilament cutting line with a regular (constant) cross section (typically a circular cross section). The trimmers are fully operator supported to try to keep the cutting line away from harmful objects that lie on or protrude from the ground. Some operators may rest the head on the ground to trim an edge closely and to relieve trimmer weight, but these actions result in wearing away the base of the head and cause skidding thrust forces from ground contact that create scalping and uneven cuts resulting from poor control of normal operating forces.
The thin monofilament cutting line requires very high speed to cut (e.g., tip speeds in the range of 25,000-30,000 ft/min). The existing monofilament cutting lines tend to break easily due to high speed impacts causing overstress failures, thereby needing constant replenishment. When common bumping mechanisms are needed to advance or replenish broken line, the operator often gouges the grass leaving an unsightly scar into evenly cut or “just-mowed” grass. To prevent this scalping, the operator must move away from the cutting zone to find a place to bump advance the head on the ground.
The use of a trimmer is desirably handheld to keep it away from the adversities of ground contact. When trying to use the head while resting on the ground to relieve weight and/or as a stabilizing means to control cutting height, the operator has very little control of the trimmer due to unwanted thrusting and skidding. Further, the base of the head grinds off, which defeats the bumping requirement for replenishment. This results in an expensive head replacement and further operator frustration.
Monofilament cutting line remains impractical for properly mowing grass. As noted, the line requires very high speeds. The line cuts only at the outer tip of the swath and does not cut on the radial face like a blade. The line suffers from high air drag loss that makes it very inefficient. It also lacks inertia and momentum due to its low mass. Monofilament line folds back very easily because it has little supporting structure other than centrifugal force. At speeds less than 24,000 ft/min., monofilament line is typically referred to as a “wet noodle” with ever decreasing cutting ability. Due to its flimsy nature, the monofilament line is easily deflected upward by the grass it is intended to mow, leaving an irregular cut height. The line cannot lift and hold the grass for a supporting cut, is very dull and mashes the grass (instead of cutting it) leaving final cut edges of the grass in an unacceptable quality. Although attempted numerous times over the years, a rotary mowing application with a mono filament line has never been successful.